Conception without the development of a human being.

Conception sometimes results in products that are not capable of developing into an embryo and fetus. This group, designated with the term gestational trophoblastic neoplasia, comprises the benign hydatidiform mole, the invasive mole (chorioadenoma destruens) and the frankly malignant variety, choriocarcinoma. Another type of atypical oocyte activation occurs in parthenogenesis. In the human, two types of tumors, dermoid cysts and teratomas, are believed to result from this process. We elucidate the generation of these abnormal growths and provide explanations as to why they cannot be regarded as human individuals or human beings. We argue that it is not the number of chromosomes that is required for a given form of human life to become a human being but rather the biparental origin of the chromosome set.